There is probably an optimum air preasure for the front bladder of each make of kite.
How hard is hard enough? An air preasure gauge connected to the pump might be a useful accessory.
I've just started on an ARX 13.5 and I'd appreciate some advice.

I use the following method:
Pump until the leading edge takes the C shape. After this point count how many "pumps" more it takes to get it hard. (depens on the kite and pump but with 20 more strokes it willl get very hard.).
Remember this number and them inflate this leading edge always the same way.
I read somewhere that a LE needs 6 psi and would resist around 15 until breakage. (notes of Ken Winner on the rhinos)

Didn't he also say that the big pumps we use deliver about 12 psi max. If someone has that messaeg could they confirm this. If the pump capacity is lower that the bladder capacity just pump away till the pump doesn't work.

Anyway thats what I do. Just pump untill it gets pretty hard to pump any more in. I'm at about the limit of my pump, with out really forcing it. This seems to work fine with Takoons. they are good and firm and I haven't blown them up....

remember that the presssure increases a lot when the tubes are heated by the sun, a friend left the struts inflated of his 17.5 arx and left it in a locked car in acapulco. Well, it blew up to say the least, he had used it once. I agree that is an extreme example, but take it into account.
Andres

I friend and I both bought F-one 12.0 Magic kites. We were having problems with the tips folding over and other floppy problems which really hampered relanuching. We bought a cheap 30 PSI pressure guage and with some tubing made an extension (with a T for the guage) where we now insert the pump nose. What we found was that 6.0 to 7 PSI is about right. I found it intimidating to pump up the main bladder this hard without the pressure guage.